Special Operating Modes - Dantherm Rcv320 P1 Benutzerhandbuch

Special operating modes

Preheating (with
preheating coil)
Defrosting
Standard
defrosting
procedure
26
In this section, the operation of the system under special conditions is described. For details
on the standard operating modes, please refer to page 9.
If a preheating coil is installed, the unit can additionally heat the outdoor air (T1) electrically to
reduce the risk of frost and increase the supply air temperature. However, if the preheating
coil cannot provide for a frost-proof heat exchanger, the defrosting program will start.
• The preheating process is controlled according to a complex algorithm involving several
sensors. The sensors constantly measure temperatures while the system keeps the energy
consumption to a minimum.
• The temperature of the outside air is increased just enough to maintain the airflow and, if
possible, to avoid that the defrosting mode is started.
• Depending on the temperature conditions, preheating increases/decreases by 10 % every
60 seconds.
The temperature setpoints during operation with an active preheating coil are fixed and
cannot be changed.
In cold conditions where the T1 outdoor air is below -3 °C and ice may form due to the
condensate in the heat exchanger, the unit will start defrosting.
INFORMATION
The defrost mode is a safety mode. During defrosting the unit cannot change to another
operating mode until defrosting is completed. When the defrost mode is active, the HRC 3
dEF
indicates on the display.
There are two different procedures for defrosting:
• no fireplace in the house (default setting)
• fireplace in the house
You can change the defrosting procedure via the PC tool. However, the setpoints for
defrosting cannot be changed.
The standard defrosting procedure without a fireplace in the house will trigger the following
steps:
• The speed of the supply air fan decreases slowly until the minimum speed is reached.
• After 10 seconds, the supply air fan switches off completely while the exhaust air fan
continues to run to defrost the ice by means of warm air from the interior rooms.
• When the defrosting process is completed, the supply air fan starts at minimum speed
and increases its speed until the originally desired speed is reached.
The defrosting process creates a negative pressure in the dwelling. Depending on the air
tightness of the dwelling, the negative pressure leads to the following:
• If the dwelling is not completely airtight, the "missing" supply air will penetrate through
small leaks in the dwelling envelope. In this case, the conditions for defrost mode are
favourable.
• If the dwelling envelope is completely airtight and the "missing" supply air cannot enter
the dwelling via other ways, defrosting is not as efficient and is only performed in low/
freezing temperature conditions. NOTICE! Under such conditions, we strongly
recommend using a preheating coil.
INSTALLATION AND SERVICE MANUAL FOR PROFESSIONALS
Product description: Special operating modes